Function getBackupFileNameFirstVersion

src/utils/fileHistory.ts:847–862

* Gets the first (earliest) backup version for a file, used when rewinding * to a target backup point where the file has not been tracked yet. * * @returns The backup file name for the first version, or null if the file * did not exist in the first version, or undefined if we cannot find a * fi

(
  trackingPath: string,
  state: FileHistoryState,
)

 * first version at all
 */
function getBackupFileNameFirstVersion(
  trackingPath: string,
  state: FileHistoryState,
): BackupFileName | undefined {
  for (const snapshot of state.snapshots) {
    const backup = snapshot.trackedFileBackups[trackingPath]
    if (backup !== undefined && backup.version === 1) {
      // This can be either a file name or null, with null meaning the file
      // did not exist in the first version.
      return backup.backupFileName
    }
  }

  // The undefined means there was an error resolving the first version.
  return undefined
}

/**
 * Use the relative path as the key to reduce session storage space for tracking.